What is the crystal structure of common salt?

Common salt, also known as sodium chloride (NaCl), has a cubic crystal structure known as face-centred cubic (FCC).

Sodium chloride, or common salt, is a type of ionic compound. It forms a crystal lattice structure that is cubic in shape, specifically a face-centred cubic (FCC) structure. This means that each sodium ion (Na+) is surrounded by six chloride ions (Cl-) and vice versa. This arrangement is due to the ionic bonding between the sodium and chloride ions, where the sodium ion donates one electron to the chloride ion, forming a strong electrostatic attraction between them.

The FCC structure of sodium chloride is highly ordered and symmetrical. Each unit cell, the smallest repeating unit of the crystal, is a cube with chloride ions at the corners and centres of each face, and sodium ions filling the gaps between them. This arrangement maximises the attraction between the oppositely charged ions and minimises the repulsion between like-charged ions, leading to a stable and tightly packed structure.

This crystal structure is responsible for many of the properties of common salt. For example, its high melting and boiling points are due to the strong ionic bonds that need a lot of energy to break. Its ability to dissolve in water is due to the polar water molecules being able to separate the sodium and chloride ions. Furthermore, when in solution or molten, it can conduct electricity as the ions are free to move and carry charge.

In summary, the crystal structure of common salt is a face-centred cubic structure, resulting from the ionic bonding between sodium and chloride ions. This structure gives salt its characteristic properties, including its high melting point, solubility in water, and ability to conduct electricity.